The Ledsjo end moraine-a subaquatic push moraine composed of glaciomarine clay in central Sweden
(2013) In Proceedings of the Geologists' Association 124(5). p.738-752- Abstract
- During the Younger Dryas cold event, the Scandinavian ice sheet readvanced in southwest Sweden and formed the Middle Swedish end-moraine zone (MSEMZ). Recent highway construction near Skara has created an exposure through the prominent ridge at Ledsjo. Through sketching and measurement of structural information, we have documented the internal character of the Ledsjo moraine. The moraine consists predominantly of clay with numerous sand pods and lenses, which show undeformed, brittle deformed, or fluidized structures. Based on geomorphology and structural geology, it is clear the moraine was made during two advances. As ice advanced, proglacial marine clay was subglacially mobilized by the ice and extruded at the ice margin forming a ramp... (More)
- During the Younger Dryas cold event, the Scandinavian ice sheet readvanced in southwest Sweden and formed the Middle Swedish end-moraine zone (MSEMZ). Recent highway construction near Skara has created an exposure through the prominent ridge at Ledsjo. Through sketching and measurement of structural information, we have documented the internal character of the Ledsjo moraine. The moraine consists predominantly of clay with numerous sand pods and lenses, which show undeformed, brittle deformed, or fluidized structures. Based on geomorphology and structural geology, it is clear the moraine was made during two advances. As ice advanced, proglacial marine clay was subglacially mobilized by the ice and extruded at the ice margin forming a ramp of debris-flow sediment. Contemporaneously, subglacial meltwater transported sand to the margin, where the meltwater became a buoyant plume, and sand was deposited near the ice margin by currents moving away from as well as toward the ice margin. These processes resulted in interbedded sand and clay. Continued advance of the ice margin deformed this package and further pushed the assemblage into a ridge form with gravity sliding of portions of the ridge. Prior to the second advance, sand was deposited on the proximal side of the initial ridge. During readvance, this sand was thrust faulted and intruded by mobilized clay. Up ice of the intruded sands, subglacial, extensional deformation created a complex shear zone of faulted sand and clay. The Ledsjo moraine represents a subaerial example of submarine push moraines like the submerged moraines recently documented in Svalbard. (c) 2012 The Geologists' Association. Published by Elsevier Ltd. All rights reserved. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/4172276
- author
- Johnson, Mark D. ; Benediktsson, Ivar Örn LU and Bjorklund, Lennart
- organization
- publishing date
- 2013
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- End moraine, Push moraine, Glaciomarine clay, Younger Dryas, Glaciotectonism
- in
- Proceedings of the Geologists' Association
- volume
- 124
- issue
- 5
- pages
- 738 - 752
- publisher
- Elsevier
- external identifiers
-
- wos:000325056500002
- scopus:84883558692
- ISSN
- 0016-7878
- DOI
- 10.1016/j.pgeola.2012.08.001
- language
- English
- LU publication?
- yes
- id
- 722b062f-69cb-4987-a536-9c169536a04a (old id 4172276)
- date added to LUP
- 2016-04-01 13:28:28
- date last changed
- 2022-02-26 21:24:55
@article{722b062f-69cb-4987-a536-9c169536a04a,
abstract = {{During the Younger Dryas cold event, the Scandinavian ice sheet readvanced in southwest Sweden and formed the Middle Swedish end-moraine zone (MSEMZ). Recent highway construction near Skara has created an exposure through the prominent ridge at Ledsjo. Through sketching and measurement of structural information, we have documented the internal character of the Ledsjo moraine. The moraine consists predominantly of clay with numerous sand pods and lenses, which show undeformed, brittle deformed, or fluidized structures. Based on geomorphology and structural geology, it is clear the moraine was made during two advances. As ice advanced, proglacial marine clay was subglacially mobilized by the ice and extruded at the ice margin forming a ramp of debris-flow sediment. Contemporaneously, subglacial meltwater transported sand to the margin, where the meltwater became a buoyant plume, and sand was deposited near the ice margin by currents moving away from as well as toward the ice margin. These processes resulted in interbedded sand and clay. Continued advance of the ice margin deformed this package and further pushed the assemblage into a ridge form with gravity sliding of portions of the ridge. Prior to the second advance, sand was deposited on the proximal side of the initial ridge. During readvance, this sand was thrust faulted and intruded by mobilized clay. Up ice of the intruded sands, subglacial, extensional deformation created a complex shear zone of faulted sand and clay. The Ledsjo moraine represents a subaerial example of submarine push moraines like the submerged moraines recently documented in Svalbard. (c) 2012 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.}},
author = {{Johnson, Mark D. and Benediktsson, Ivar Örn and Bjorklund, Lennart}},
issn = {{0016-7878}},
keywords = {{End moraine; Push moraine; Glaciomarine clay; Younger Dryas; Glaciotectonism}},
language = {{eng}},
number = {{5}},
pages = {{738--752}},
publisher = {{Elsevier}},
series = {{Proceedings of the Geologists' Association}},
title = {{The Ledsjo end moraine-a subaquatic push moraine composed of glaciomarine clay in central Sweden}},
url = {{http://dx.doi.org/10.1016/j.pgeola.2012.08.001}},
doi = {{10.1016/j.pgeola.2012.08.001}},
volume = {{124}},
year = {{2013}},
}